Thin films of tungsten oxide (WO3) were deposited on GZO-coated B270 glass substrates and thin films of Ta<sub>2</sub>O<sub>5</sub> were
deposited on B270 glass substrates by electron beam gun evaporation at high vacuum pressure of 3×10<sup>-5</sup> Torr and varied
oxygen pressures ranging from 1.0×10<sup>-4</sup> to 6.0×10<sup>-4</sup> Torr. The optical properties of the electro-chromic (EC) film were
measured by a spectrophotometer. The optical modulation (ΔT) of the tungsten oxide thin film deposited at an oxygen
pressure of 1.0×10<sup>-4</sup> Torr was found to be ΔT = 67.46% at λ=550nm. The optimum optical properties for deposition of
Ta<sub>2</sub>O<sub>5</sub> were attained at an oxygen pressure of 4x10<sup>-4</sup> Torr. Gallium doped zinc oxide (GZO) was used as a conductive
layer instead of ITO. A five layer EC device (Glass/GZO/WO<sub>3</sub>/Ta<sub>2</sub>O<sub>5</sub>/NiO/Al) has been design and fabricated.